Reducing Toxic Air Pollutants

Toxic air pollutants, or air toxics, are known to cause
or are suspected of causing cancer, birth defects,
reproduction problems, and other serious illnesses.
Exposure to certain levels of some toxic air pollutants
can cause difficulty in breathing, nausea or other
illnesses. Exposure to certain toxic pollutants can
even cause death.

Persistent Bioaccumulative
Toxics (PBTs)

PBTs such as mercury and DDT last for a long time in the
environment with little change in their structure or toxic
effects. This means that a persistent toxic chemical transported
in the wind can be just as toxic 10,000 miles away
as it was at the smokestack from which it was released.
Some PBTs, such as polychlorinated biphenyls (PCBs),
have been found in remote parts of the Arctic, far away
from the industrial sources that produce them.

Some of the PBTs that move through the air are deposited
into water bodies and are concentrate up through the food
chain, harming fish-eating animals and people. Small fish
may consume plants that live in water contaminated by
PBTs, which are absorbed into plant tissues. Big fish eat
smaller fish and as the PBTs pass up the food chain, their
levels go up. So a large fish consumed by people may have
a much higher concentration of PBTs in its tissues than the
simple plant first absorbing the PBTs. PBTs can concentrate
in big fish to levels thousands of times the levels found in
the contaminated water.

Over 2000 U.S. water bodies are covered by fish consumption
advisories, warning people not to eat the fish because
of contamination with chemicals, usually PBTs. Those
compounds have been linked to illnesses such as cancer,
birth defects, and nervous system disorders.

The 1990 Clean Air Act gave EPA the authority to reduce
PBT levels by requiring pollution sources to install control
devices or change production methods.

Some toxic air pollutants are of concern because
they degrade slowly or not at all, as in the case of
metals such as mercury or lead. These persistent air
toxics can remain in the environment for a long time
and can be transported great distances. Toxic air
pollutants, like mercury or polychlorinated biphenyls,
deposited onto soil or into lakes and streams persist
and bioaccumulate in the environment. They can
affect living systems and food chains, and eventually
affect people when they eat contaminated food. This
can be particularly important for American Indians
or other communities where cultural practices or
subsistence life styles are prevalent.

The majority of air toxics come from manmade
sources, such as factory smokestack emissions and
motor vehicle exhaust.

Gasoline also contains air toxics. When you put fuel in
your car, gases escape and form a vapor. You can smell
these vapors when you refuel your vehicle.

When cars and trucks burn gasoline, toxic air
pollutants are emitted from the tailpipe. Those air
toxics are combustion products-chemicals that are
produced when gasoline is burned. EPA is working
with industries to develop cleaner-burning fuels and
more efficient engines, and is taking steps to make
sure that pollution control devices installed in motor
vehicles work properly. EPA has issued requirements
that are leading to cleaner-burning diesel engines,
reducing releases of particle pollution and air toxics.

Air toxics are also released from industrial sources,
such as chemical factories, refineries, and incinerators,
and even from small industrial and commercial
sources, such as dry cleaners and printing shops.
Under the 1990 Clean Air Act, EPA has regulated both
large and small sources of air toxics, but has mainly
focused efforts on larger sources.

Before the 1990 Clean Air Act Amendments, EPA
regulated air toxics one chemical at a time. This
approach did not work well. Between 1970 and 1990,
EPA established regulations for only seven pollutants.
The 1990 Clean Air Act Amendments took a completely
different approach to reducing toxic air pollutants. The
Amendments required EPA to identify categories of
industrial sources for 187 listed toxic air pollutants and
to take steps to reduce pollution by requiring sources
to install controls or change production processes. It
makes good sense to regulate by categories of industries
rather than one pollutant at a time, since many
individual sources release more than one toxic chemical.
Developing controls and process changes for industrial
source categories can result in major reductions in
releases of multiple pollutants at one time.

EPA has published regulations covering a wide range
of industrial categories, including chemical plants,
incinerators, dry cleaners, and manufacturers of wood
furniture. Harmful air toxics from large industrial
sources, such as chemical plants, petroleum refineries,
and paper mills, have been reduced by nearly 70
percent. These regulations mostly apply to large,
so-called "major" sources and also to some smaller
sources known as "area" sources. In most cases, EPA
does not prescribe a specific control technology, but
sets a performance level based on a technology or
other practices already used by the better-controlled
and lower emitting sources in an industry. EPA works
to develop regulations that give companies as much
flexibility as possible in deciding how they reduce
their toxic air emissions-as long as the companies
meet the levels required in the regulations.

The 1990 Clean Air Act requires EPA to first set
regulations using a technology-based or performance-based
approach to reduce toxic emissions from
industrial sources. After EPA sets the technology-based
regulations, the Act requires EPA to evaluate
any remaining ("residual") risks, and decide whether
it is necessary to control the source further. That
assessment of remaining risk was initiated in the
year 2000 for some of the industries covered by the
technology-based standards.

Chemical Emergencies

The 1984 chemical disaster that resulted in thousands
of deaths in Bhopal, India, inspired sections of the 1990
Clean Air Act that require factories and other businesses
to develop plans to prevent accidental releases
of highly toxic chemicals.

The 1990 Act also established the Chemical Safety
Board, an independent agency that investigates and
reports on accidental releases of toxic chemicals from
industrial facilities. The Board operates much like the
National Transportation Safety Board, the agency that
investigates airplane and train crashes. The Chemical
Safety Board assembles the information necessary to
determine how and why an accident involving toxic
chemicals happened. The goal is to apply understanding
of accidents to prevent other accidents involving
toxic chemicals.

Air Toxics and Risk

The Clean Air Act requires a number of studies to help
EPA better characterize risks to human health and the
environment from air toxics. Those studies provide
information for rulemaking and support national
and local efforts to address risks through pollution
prevention and other voluntary programs. Among
these risk reduction initiatives are:

The Integrated Urban Air Toxics Strategy includes
local and community-based initiatives to reduce local
toxic air emissions. The primary goal of the strategy
is to reduce public health risks from both indoor
and outdoor sources of toxic air pollutants. More
information can be found at www.epa.gov/ttn/atw.

The Great Waters Program incorporates activities
to investigate and reduce the deposition of toxic
air pollutants to the "Great Waters," which include
the Chesapeake Bay, Lake Champlain, the Great
Lakes, National Estuary Program areas, and National
Estuarine Research Reserves. To learn more, visit
www.epa.gov/glnpo.